Q&A: A Forum for Green Building Experts and Beginners

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!

6 Answers

Roof membrane and live vegetative roof

Hey all,

So after Material quotes and city grants etc, it looks like its going to be viable go me to do a live vegatative roof (green roof) on the flat roof I've recently built.

now I'm thinking about what roofing membrane to put on, to go under the green roof. I am considering things like cost, longevity, ease of install, potential for leaks etc.

I'm in climate zone 6. My potential roof assembly is as follows:

9.5" I joists with R31 rockwool batting
3/4 plywood decking
6" polyiso at R34
1/2" roofboard
Roofing membrane ***
3" green roof assembly

Asked By Jamie B | Nov 18 17
4 Answers

Insulate a Cabin to last

Martin - I've learned a tremendous from you & GBA. This is a 1st asking a question. I'm also an engineer & lic Home Inspector, and I see what happens to homes.
I'm current building a cabin in northern Hayward, WI (Zone 7). I'm on a slab, 20'x26', 1 1/2 story, 2x6 walls 16" OC. I had a local carpenter put up the shell, and the rest is up to me. The cabin is sheathed in OSB, Tyvek, Fascia/soffit, and Anderson windows & door are in. I installed kraft faced R19 Batts in the walls (drywall & siding are not yet installed).

Asked By Dan Musielski | Nov 16 17
2 Answers

GBA Construction Details criticism & question

First, I thoroughly appreciate the effort to organize and share a large volume of quality construction details on GBA. Excellent information.
However, I'm disappointed that the .dwg versions of details are incredibly time consuming to work with for the following reasons:

1. Details and objects are completely exploded which makes them very inefficient to work with and revise. Leader arrows are not even singular entities and are exploded into 4 separate objects. Hatches are often dozens of exploded objects which is painful to select in order to edit.

Asked By Spencer Decker | Nov 15 17
4 Answers

Best way to insulate attic

My attic currently has R19 foil faced fiberglass batts installed. I would like to air seal the entire attic and re-insulate with blown in cellulose.
The original plan was to cut EPS to fit between the stud bays and seal with great stuff, followed by the fiberglass and blown cellulose. From my understanding, EPS or any rigid foam is not worth the labor for this particular application.

Should I remove the fiberglass batts, caulk/foam the seams and openings, and then reuse the fiberglass followed by cellulose?

Asked By craziekeiichi | Nov 13 17
5 Answers

Please Help!!! Dimple membrane a necessity?

Asked By Rasheed Warith | Nov 14 17
10 Answers

Question on direct vent fireplaces

I am gut renovating and expanding a circa 1920 cottage. I am trying to get as close to net zero as I can. I am an architect fairly well-versed in the principles and techniques of net-zero, DER and Passivhaus my firm having designed and built two Passivhaus and 13 net zero homes, all of which have had their performance measured and verified. The point of this bragg-y credentializing is to head off the inevitable finger wagging that usually comes upon mention of the very idea of including a fireplace in a home that aspires to net zero. I get it. Not a good idea.

Asked By user-6954517 | Nov 18 17
8 Answers

Sizing a ductless minisplit for heating

Hi all,

I'm going to install a ductless heat pump. I settled on LG Art Cool Premier (HYV1 or HYV2). Now I need to figure out system size, and there is too much info.

I have 550 sf addition built in late '80s, which is a split lever open space, and is VERY cold (i've attached some photos)!

It has a large french door (8x10' glass, 3 sections), 7 windows, and 5 skylights. All are double glass.

Asked By Levab | Nov 16 17
8 Answers

Petrol-free home: Petrol-free housewrap

So I've got a plan that promotes petrol-free materials throughout the lion's share of the rehab of my shed, which is a lead-in project to the rehab of my house. It involves now a metal roof; Pavatex as a insulation above the roof rafters and Roxul between the rafters; Airkrete in the wall cavity; and Foamglas beneath the Rosendale Cement-based concrete slab.

Main remaining urgent challenge to get the plans to the buildings department ASAP as far as I can tell: "house wrap" "vapor barrier" situation.

Asked By Gregg Zuman | Nov 15 17
2 Answers

Foil vs Bubble Foil or Foam Foil

Hi I'm insulating a shed-like structure on my property to create a comfortable living space. With regard to the tin roof I've been advised to use a layer of Bubble foil on the battens directly underneath the tin and then below that in the remaining ceiling space (above the plasterboard) Fibreglass batts. My question is: In this kind of context will bubble foil give an improved insulating performance over and above foil (sisilation) on it's own directly under the tin? i.e. Is bubble foil worthy of the added cost??

Asked By AussieQ | Nov 15 17
5 Answers

Possible to use Vented attic in conjunction with Open cell spray foam?

Hello there,
I am a General Contractor in Miami, FL (Hot and humid weather!) and I may get screamed at for asking this question, but is it possible to use continuous ventilation at the soffits (vented attic) in conjunction with Open cell spray foam (sprayed to the underside of the roof sheathing)?

Asked By 5221lefty | Nov 15 17
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!